/**
 * @author spidersharma / http://eduperiment.com/
 */

import {
	AdditiveBlending,
	Color,
	LinearFilter,
	MeshBasicMaterial,
	RGBAFormat,
	ShaderMaterial,
	UniformsUtils,
	Vector2,
	Vector3,
	WebGLRenderTarget
} from "./three.module";
import { Pass } from "./Pass";
import { CopyShader } from "./CopyShader";
import { LuminosityHighPassShader } from "./LuminosityHighPassShader";

/**
 * UnrealBloomPass is inspired by the bloom pass of Unreal Engine. It creates a
 * mip map chain of bloom textures and blurs them with different radii. Because
 * of the weighted combination of mips, and because larger blurs are done on
 * higher mips, this effect provides good quality and performance.
 *
 * Reference:
 * - https://docs.unrealengine.com/latest/INT/Engine/Rendering/PostProcessEffects/Bloom/
 */
var UnrealBloomPass = function (resolution, strength, radius, threshold) {

	Pass.call(this);

	this.strength = (strength !== undefined) ? strength : 1;
	this.radius = radius;
	this.threshold = threshold;
	this.resolution = (resolution !== undefined) ? new Vector2(resolution.x, resolution.y) : new Vector2(256, 256);

	// create color only once here, reuse it later inside the render function
	this.clearColor = new Color(0, 0, 0);

	// render targets
	var pars = { minFilter: LinearFilter, magFilter: LinearFilter, format: RGBAFormat };
	this.renderTargetsHorizontal = [];
	this.renderTargetsVertical = [];
	this.nMips = 5;
	var resx = Math.round(this.resolution.x / 2);
	var resy = Math.round(this.resolution.y / 2);

	this.renderTargetBright = new WebGLRenderTarget(resx, resy, pars);
	this.renderTargetBright.texture.name = "UnrealBloomPass.bright";
	this.renderTargetBright.texture.generateMipmaps = false;

	for (var i = 0; i < this.nMips; i++) {

		var renderTargetHorizonal = new WebGLRenderTarget(resx, resy, pars);

		renderTargetHorizonal.texture.name = "UnrealBloomPass.h" + i;
		renderTargetHorizonal.texture.generateMipmaps = false;

		this.renderTargetsHorizontal.push(renderTargetHorizonal);

		var renderTargetVertical = new WebGLRenderTarget(resx, resy, pars);

		renderTargetVertical.texture.name = "UnrealBloomPass.v" + i;
		renderTargetVertical.texture.generateMipmaps = false;

		this.renderTargetsVertical.push(renderTargetVertical);

		resx = Math.round(resx / 2);

		resy = Math.round(resy / 2);

	}

	// luminosity high pass material

	if (LuminosityHighPassShader === undefined)
		console.error("UnrealBloomPass relies on LuminosityHighPassShader");

	var highPassShader = LuminosityHighPassShader;
	this.highPassUniforms = UniformsUtils.clone(highPassShader.uniforms);

	this.highPassUniforms["luminosityThreshold"].value = threshold;
	this.highPassUniforms["smoothWidth"].value = 0.01;

	this.materialHighPassFilter = new ShaderMaterial({
		uniforms: this.highPassUniforms,
		vertexShader: highPassShader.vertexShader,
		fragmentShader: highPassShader.fragmentShader,
		defines: {}
	});

	// Gaussian Blur Materials
	this.separableBlurMaterials = [];
	var kernelSizeArray = [3, 5, 7, 9, 11];
	var resx = Math.round(this.resolution.x / 2);
	var resy = Math.round(this.resolution.y / 2);

	for (var i = 0; i < this.nMips; i++) {

		this.separableBlurMaterials.push(this.getSeperableBlurMaterial(kernelSizeArray[i]));

		this.separableBlurMaterials[i].uniforms["texSize"].value = new Vector2(resx, resy);

		resx = Math.round(resx / 2);

		resy = Math.round(resy / 2);

	}

	// Composite material
	this.compositeMaterial = this.getCompositeMaterial(this.nMips);
	this.compositeMaterial.uniforms["blurTexture1"].value = this.renderTargetsVertical[0].texture;
	this.compositeMaterial.uniforms["blurTexture2"].value = this.renderTargetsVertical[1].texture;
	this.compositeMaterial.uniforms["blurTexture3"].value = this.renderTargetsVertical[2].texture;
	this.compositeMaterial.uniforms["blurTexture4"].value = this.renderTargetsVertical[3].texture;
	this.compositeMaterial.uniforms["blurTexture5"].value = this.renderTargetsVertical[4].texture;
	this.compositeMaterial.uniforms["bloomStrength"].value = strength;
	this.compositeMaterial.uniforms["bloomRadius"].value = 0.1;
	this.compositeMaterial.needsUpdate = true;

	var bloomFactors = [1.0, 0.8, 0.6, 0.4, 0.2];
	this.compositeMaterial.uniforms["bloomFactors"].value = bloomFactors;
	this.bloomTintColors = [new Vector3(1, 1, 1), new Vector3(1, 1, 1), new Vector3(1, 1, 1),
	new Vector3(1, 1, 1), new Vector3(1, 1, 1)];
	this.compositeMaterial.uniforms["bloomTintColors"].value = this.bloomTintColors;

	// copy material
	if (CopyShader === undefined) {

		console.error("UnrealBloomPass relies on CopyShader");

	}

	var copyShader = CopyShader;

	this.copyUniforms = UniformsUtils.clone(copyShader.uniforms);
	this.copyUniforms["opacity"].value = 1.0;

	this.materialCopy = new ShaderMaterial({
		uniforms: this.copyUniforms,
		vertexShader: copyShader.vertexShader,
		fragmentShader: copyShader.fragmentShader,
		blending: AdditiveBlending,
		depthTest: false,
		depthWrite: false,
		transparent: true
	});

	this.enabled = true;
	this.needsSwap = false;

	this.oldClearColor = new Color();
	this.oldClearAlpha = 1;

	this.basic = new MeshBasicMaterial();

	this.fsQuad = new Pass.FullScreenQuad(null);

};

UnrealBloomPass.prototype = Object.assign(Object.create(Pass.prototype), {

	constructor: UnrealBloomPass,

	dispose: function () {

		for (var i = 0; i < this.renderTargetsHorizontal.length; i++) {

			this.renderTargetsHorizontal[i].dispose();

		}

		for (var i = 0; i < this.renderTargetsVertical.length; i++) {

			this.renderTargetsVertical[i].dispose();

		}

		this.renderTargetBright.dispose();

	},

	setSize: function (width, height) {

		var resx = Math.round(width / 2);
		var resy = Math.round(height / 2);

		this.renderTargetBright.setSize(resx, resy);

		for (var i = 0; i < this.nMips; i++) {

			this.renderTargetsHorizontal[i].setSize(resx, resy);
			this.renderTargetsVertical[i].setSize(resx, resy);

			this.separableBlurMaterials[i].uniforms["texSize"].value = new Vector2(resx, resy);

			resx = Math.round(resx / 2);
			resy = Math.round(resy / 2);

		}

	},

	render: function (renderer, writeBuffer, readBuffer, deltaTime, maskActive) {

		this.oldClearColor.copy(renderer.getClearColor());
		this.oldClearAlpha = renderer.getClearAlpha();
		var oldAutoClear = renderer.autoClear;
		renderer.autoClear = false;

		renderer.setClearColor(this.clearColor, 0);

		if (maskActive) renderer.state.buffers.stencil.setTest(false);

		// Render input to screen

		if (this.renderToScreen) {

			this.fsQuad.material = this.basic;
			this.basic.map = readBuffer.texture;

			renderer.setRenderTarget(null);
			renderer.clear();
			this.fsQuad.render(renderer);

		}

		// 1. Extract Bright Areas

		this.highPassUniforms["tDiffuse"].value = readBuffer.texture;
		this.highPassUniforms["luminosityThreshold"].value = this.threshold;
		this.fsQuad.material = this.materialHighPassFilter;

		renderer.setRenderTarget(this.renderTargetBright);
		renderer.clear();
		this.fsQuad.render(renderer);

		// 2. Blur All the mips progressively

		var inputRenderTarget = this.renderTargetBright;

		for (var i = 0; i < this.nMips; i++) {

			this.fsQuad.material = this.separableBlurMaterials[i];

			this.separableBlurMaterials[i].uniforms["colorTexture"].value = inputRenderTarget.texture;
			this.separableBlurMaterials[i].uniforms["direction"].value = UnrealBloomPass.BlurDirectionX;
			renderer.setRenderTarget(this.renderTargetsHorizontal[i]);
			renderer.clear();
			this.fsQuad.render(renderer);

			this.separableBlurMaterials[i].uniforms["colorTexture"].value = this.renderTargetsHorizontal[i].texture;
			this.separableBlurMaterials[i].uniforms["direction"].value = UnrealBloomPass.BlurDirectionY;
			renderer.setRenderTarget(this.renderTargetsVertical[i]);
			renderer.clear();
			this.fsQuad.render(renderer);

			inputRenderTarget = this.renderTargetsVertical[i];

		}

		// Composite All the mips

		this.fsQuad.material = this.compositeMaterial;
		this.compositeMaterial.uniforms["bloomStrength"].value = this.strength;
		this.compositeMaterial.uniforms["bloomRadius"].value = this.radius;
		this.compositeMaterial.uniforms["bloomTintColors"].value = this.bloomTintColors;

		renderer.setRenderTarget(this.renderTargetsHorizontal[0]);
		renderer.clear();
		this.fsQuad.render(renderer);

		// Blend it additively over the input texture

		this.fsQuad.material = this.materialCopy;
		this.copyUniforms["tDiffuse"].value = this.renderTargetsHorizontal[0].texture;

		if (maskActive) renderer.state.buffers.stencil.setTest(true);

		if (this.renderToScreen) {

			renderer.setRenderTarget(null);
			this.fsQuad.render(renderer);

		} else {

			renderer.setRenderTarget(readBuffer);
			this.fsQuad.render(renderer);

		}

		// Restore renderer settings

		renderer.setClearColor(this.oldClearColor, this.oldClearAlpha);
		renderer.autoClear = oldAutoClear;

	},

	getSeperableBlurMaterial: function (kernelRadius) {

		return new ShaderMaterial({

			defines: {
				"KERNEL_RADIUS": kernelRadius,
				"SIGMA": kernelRadius
			},

			uniforms: {
				"colorTexture": { value: null },
				"texSize": { value: new Vector2(0.5, 0.5) },
				"direction": { value: new Vector2(0.5, 0.5) }
			},

			vertexShader:
				"varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

			fragmentShader:
				"#include <common>\
				varying vec2 vUv;\n\
				uniform sampler2D colorTexture;\n\
				uniform vec2 texSize;\
				uniform vec2 direction;\
				\
				float gaussianPdf(in float x, in float sigma) {\
					return 0.39894 * exp( -0.5 * x * x/( sigma * sigma))/sigma;\
				}\
				void main() {\n\
					vec2 invSize = 1.0 / texSize;\
					float fSigma = float(SIGMA);\
					float weightSum = gaussianPdf(0.0, fSigma);\
					vec3 diffuseSum = texture2D( colorTexture, vUv).rgb * weightSum;\
					for( int i = 1; i < KERNEL_RADIUS; i ++ ) {\
						float x = float(i);\
						float w = gaussianPdf(x, fSigma);\
						vec2 uvOffset = direction * invSize * x;\
						vec3 sample1 = texture2D( colorTexture, vUv + uvOffset).rgb;\
						vec3 sample2 = texture2D( colorTexture, vUv - uvOffset).rgb;\
						diffuseSum += (sample1 + sample2) * w;\
						weightSum += 2.0 * w;\
					}\
					gl_FragColor = vec4(diffuseSum/weightSum, 1.0);\n\
				}"
		});

	},

	getCompositeMaterial: function (nMips) {

		return new ShaderMaterial({

			defines: {
				"NUM_MIPS": nMips
			},

			uniforms: {
				"blurTexture1": { value: null },
				"blurTexture2": { value: null },
				"blurTexture3": { value: null },
				"blurTexture4": { value: null },
				"blurTexture5": { value: null },
				"dirtTexture": { value: null },
				"bloomStrength": { value: 1.0 },
				"bloomFactors": { value: null },
				"bloomTintColors": { value: null },
				"bloomRadius": { value: 0.0 }
			},

			vertexShader:
				"varying vec2 vUv;\n\
				void main() {\n\
					vUv = uv;\n\
					gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n\
				}",

			fragmentShader:
				"varying vec2 vUv;\
				uniform sampler2D blurTexture1;\
				uniform sampler2D blurTexture2;\
				uniform sampler2D blurTexture3;\
				uniform sampler2D blurTexture4;\
				uniform sampler2D blurTexture5;\
				uniform sampler2D dirtTexture;\
				uniform float bloomStrength;\
				uniform float bloomRadius;\
				uniform float bloomFactors[NUM_MIPS];\
				uniform vec3 bloomTintColors[NUM_MIPS];\
				\
				float lerpBloomFactor(const in float factor) { \
					float mirrorFactor = 1.2 - factor;\
					return mix(factor, mirrorFactor, bloomRadius);\
				}\
				\
				void main() {\
					gl_FragColor = bloomStrength * ( lerpBloomFactor(bloomFactors[0]) * vec4(bloomTintColors[0], 1.0) * texture2D(blurTexture1, vUv) + \
													 lerpBloomFactor(bloomFactors[1]) * vec4(bloomTintColors[1], 1.0) * texture2D(blurTexture2, vUv) + \
													 lerpBloomFactor(bloomFactors[2]) * vec4(bloomTintColors[2], 1.0) * texture2D(blurTexture3, vUv) + \
													 lerpBloomFactor(bloomFactors[3]) * vec4(bloomTintColors[3], 1.0) * texture2D(blurTexture4, vUv) + \
													 lerpBloomFactor(bloomFactors[4]) * vec4(bloomTintColors[4], 1.0) * texture2D(blurTexture5, vUv) );\
				}"
		});

	}

});

UnrealBloomPass.BlurDirectionX = new Vector2(1.0, 0.0);
UnrealBloomPass.BlurDirectionY = new Vector2(0.0, 1.0);

export { UnrealBloomPass };
